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Audiolab DC Block

I’m sure some may have a better experience than me. I tried the audiolab dc blockers with my marantz pm7000n many months ago when I still had it. It seemed to have taken away the dynamics of the sound. With some tracks, I found that it made them sound more detailed. In any case, after a week of using it - returned it.
 
n20nine said:
I’m sure some may have a better experience than me. I tried the audiolab dc blockers with my marantz pm7000n many months ago when I still had it. It seemed to have taken away the dynamics of the sound. With some tracks, I found that it made them sound more detailed. In any case, after a week of using it - returned it.
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Interesting but did it remove any hum as that is what it was designed for? Did you have transformer noise?
 
n20nine said:
I’m sure some may have a better experience than me. I tried the audiolab dc blockers with my marantz pm7000n many months ago when I still had it. It seemed to have taken away the dynamics of the sound. With some tracks, I found that it made them sound more detailed. In any case, after a week of using it - returned it.
Click to expand...

Interesting. Maybe it was the filtering circuit part that removes RFI/EMI contaminants from the mains supply in the DC blocker affecting the Marantz subjectively. Pity one can’t buy just the pure DC blocker version, without the extra bits. Was going to get one for my ‘new’ Supernait 2, but fortunately it doesn’t hum as badly as I expected, though as its in a nearfield bedroom system it still has to be turned off so I can sleep at night! Might be worth you looking into an alternative option :

https://sjostromaudio.net/shop/main...toroidal-transformers-heavy-duty-version.html
 
It is the 'extra bits' that interest me. The thought being that it is the shape of the current waveforms drawn by the rectifiers after the transformer that create the harmonics of 50Hz that make 'buzz' more audible. Which isn't directly actually a 'dc' problem.
 
Somewhere I read that DC offset doesn't affect constant current devices to the same extent - e.g. valve amps or class A integrateds, whose power demands are fairly constant irrespective of operation. Can anyone confirm or refute this claim? And would something like the Audiolab DC blocker throttle a large class A integrated such as mine? I mentioned elsewhere that it has the tiniest bit of hum from its non-torroidal transformer. Nothing in the same ballpark as (say) a NAP250, but enough that you can hear it, especially if you have it located on certain kinds of furniture (e.g. my oak sideboard, which seems to amplify that hum).

I'm probably going to be able to get one from a local dealer anyway, but if it's a no-no I might save myself the hassle....
 
JTC said:
Somewhere I read that DC offset doesn't affect constant current devices to the same extent - e.g. valve amps or class A integrateds, whose power demands are fairly constant irrespective of operation. Can anyone confirm or refute this claim?
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I've also read that buzzing is less likely if the transformer isn't idling. Sadly, it hasn't proved true in my system. I have two power amps with big toroids: a class AB Lexicon, and a recently acquired class A Pass. The Lexicon has buzzed since I moved to this house a year ago. It turns out the Pass also buzzes here, despite the fact that the transformer is nowhere near idling - it draws 300 watts continuous.
 
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About the same continuous draw as mine. I'll see if I can borrow one for a week or two.
 
JTC said:
Somewhere I read that DC offset doesn't affect constant current devices to the same extent - e.g. valve amps or class A integrateds, whose power demands are fairly constant irrespective of operation. Can anyone confirm or refute this claim?
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The hum can be due to the transfomer *mechanically* vibrating with the current though it. In effect you then get a mechanical buzz. If the output to the rest of the unit is rectified the result for the valves, etc, may essentially be DC and OK, but the current in the transformer is a series of 'bursts' as each half-cycle briefly charges up smoothing caps in the unit. So you get mechanical noises from the transformer, not electronic hum/buzz on the unit's electronic output.
 
Ok, picked up a used one to try. Didn’t really do anything obvious on the cd transport but on the integrated amp, wouldcha believe it, it does appear to have a quite noticeable impact. I’m inclined to say positive, though it may just be ‘different’ and indeed may also turn out to be placebo. Worth the punt, but I’ll give it a week or two and then remove it, see if it’s all in my head!!
 
JTC said:
Ok, picked up a used one to try. Didn’t really do anything obvious on the cd transport but on the integrated amp, wouldcha believe it, it does appear to have a quite noticeable impact. I’m inclined to say positive, though it may just be ‘different’ and indeed may also turn out to be placebo. Worth the punt, but I’ll give it a week or two and then remove it, see if it’s all in my head!!
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so how much did you pay for it?
 
JTC said:
Somewhere I read that DC offset doesn't affect constant current devices to the same extent - e.g. valve amps or class A integrateds, whose power demands are fairly constant irrespective of operation. Can anyone confirm or refute this claim? ...
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Not really true, valve amps tend to use E or less-often C core transformers, which don't seem so prone to vibrate audibly when saturated by DC offset, this doesn't mean they're not working suboptimally. High quality valve amps that have transformers actually designed for UK 240VAC may also simply have more margin before saturation kicks in. Were the constancy-of-draw argument correct, class A solid state would also be largely immune, but very much is not.
 
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JTC said:
Ok, picked up a used one to try. Didn’t really do anything obvious on the cd transport but on the integrated amp, wouldcha believe it, it does appear to have a quite noticeable impact. I’m inclined to say positive, though it may just be ‘different’ and indeed may also turn out to be placebo. Worth the punt, but I’ll give it a week or two and then remove it, see if it’s all in my head!!
Click to expand...
Might give it a try myself
 
It’s almost new. Previous owner didn’t find it helped in their situation, and it is totally mint so at the price I daresay I’d get my money back.

Mind you, based on this, I’m almost tempted to get another!
 
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